[Powertop] [PATCH] perf_bundle: introduce fixup_sample_trace_cpu()

Could you please test this patch? struct perf_sample's trace cpu is a raw_smp_processor_id() (as requsted by PERF_SAMPLE_CPU) by the time of perf_event_output() call, which may differ from original struct perf_event's cpu. thus we need to fix sample->trace.cpu via fixup_sample_trace_cpu() call. debugging output has demonstrated that some events (namely cpu_frequency) were routed incorrectly (sample->trace.cpu != pevent_get_field_val("cpu_id")): fix [cpu_frequency] cpu_nr from 1 to 0 fix [cpu_frequency] cpu_nr from 1 to 0 fix [cpu_frequency] cpu_nr from 1 to 2 fix [cpu_frequency] cpu_nr from 1 to 2 fix [cpu_frequency] cpu_nr from 1 to 3 fix [cpu_frequency] cpu_nr from 1 to 3 fix [cpu_frequency] cpu_nr from 1 to 0 fix [cpu_frequency] cpu_nr from 1 to 0 fix [cpu_frequency] cpu_nr from 1 to 2 fix [cpu_frequency] cpu_nr from 1 to 2 fix [cpu_frequency] cpu_nr from 1 to 0 fix [cpu_frequency] cpu_nr from 1 to 0 fix [cpu_frequency] cpu_nr from 1 to 0 Thanks for reporting and tracking this down to (not in any particular order): Shaojie Sun, Jon Medhurst, Sanjay Rawat, SunShaoJie. Cc: Shaojie Sun <shaojie.sun(a)linaro.org&gt; Cc: Jon Medhurst <jon.medhurst(a)linaro.org&gt; Cc: Sanjay Rawat <sanjay.rawat(a)linaro.org&gt; Cc: SunShaoJie <sunshaojie(a)huawei.com&gt; Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky(a)gmail.com&gt; --- diff --git a/src/perf/perf_bundle.cpp b/src/perf/perf_bundle.cpp index 8d480e8..b0e982b 100644 --- a/src/perf/perf_bundle.cpp +++ b/src/perf/perf_bundle.cpp @@ -285,6 +285,31 @@ static bool event_sort_function (void *i, void *j) return (timestamp(I)<timestamp(J)); } +/* + * sample's PERF_SAMPLE_CPU cpu nr is a raw_smp_processor_id() by the + * time of perf_event_output(), which may differ from struct perf_event + * cpu, thus we need to fix sample->trace.cpu. + */ +static void fixup_sample_trace_cpu(struct perf_sample *sample) +{ + struct event_format *event; + struct pevent_record rec; + unsigned long long cpu_nr; + int type; + int ret; + + rec.data = &sample->data; + type = pevent_data_type(perf_event::pevent, &rec); + event = pevent_find_event(perf_event::pevent, type); + if (!event) + return; + /** don't touch trace if event does not contain cpu_id field*/ + ret = pevent_get_field_val(NULL, event, "cpu_id", &rec, &cpu_nr, 0); + if (ret < 0) + return; + sample->trace.cpu = cpu_nr; +} + void perf_bundle::process(void) { unsigned int i; @@ -309,6 +334,7 @@ void perf_bundle::process(void) if (sample->header.type != PERF_RECORD_SAMPLE) continue; + fixup_sample_trace_cpu(sample); handle_trace_point(&sample->data, sample->trace.cpu, sample->trace.time); } }